WO2017219152A1

WO2017219152A1 - Polymeric film useful as water vapor barrier

Info

Publication number: WO2017219152A1
Application number: PCT/CH2016/000095
Authority: WO
Inventors: Stefan Bokorny; Tobias Maienfisch; Samuel C. HESS; Corinne J. HOFER; Wendelin J. Stark
Original assignee: Perlen Converting Ag
Priority date: 2016-06-22
Filing date: 2016-06-22
Publication date: 2017-12-28

Abstract

The polymeric film is useful as water vapor barrier. It comprises a (i) first layer consisting essentially of a polymer chosen from the group of: cyclic olefin copolymer, polypropylene and polyethylene; and (ii) a second layer placed on one of the surfaces of the first layer, the second layer comprising a polymer chosen from the group of: cyclic olefin copolymer, polypropylene and polyethylene, as a matrix in which a plurality of desiccant particles is embedded. The polymers of the first and second layer are of the same type. The polymeric film according to the invention is useful for pharmaceutical and medical packaging, in particular blister packaging.

Description

Polymeric film useful as water vapor barrier

The invention relates to a polymeric film useful as water vapor barrier according to the preamble of claim 1.

BACKGROUND OF THE INVENTION

Applications in the area of electronic, automotive, pharmaceutical, diagnostic and food packaging often require very low humidity levels inside the package to protect moisture- sensitive products or components from exposure to environmental humidity.

The polymer which is currently used most frequently in the area of blister packaging is polyvinylchloride (PVC). To increase the water vapor barrier the PVC bottom film is often covered by polyvinylidene chloride (PVdC). Due to ecological reasons the question of using halogen containing materials get more and more important because of their environmental impact during manufacturing and disposal.

Therefore halogen free polymers such as cyclic olefin copolymers exhibiting a similar low water vapor transmission rate (WVTR) as PVdC have been developed. Since no polymer so far was able to block moisture completely, chemical desiccants have been applied broadly to create an effective zero relative humidity atmosphere.

Incorporating active ingredients into a polymeric matrix has been studied previously and is described in a number of patent documents. In WO 2004/000541 A1 and WO 2044/080808 A2 for example, multilayer systems are described, which consist of layers of different polymers combined with various desiccants. The active ingredients incorporated within the polymeric matrix reach from physical desiccants like zeolites to chemical desiccants like salts (CaC½, NaCl) and metal oxides like CaO. Very problematic but important is the specific combination of a particular polymer and a defined desiccant, as variations in physical and chemical properties enormously influence the ability of dispersing desiccant particles within a polymeric matrix. Additionally the combination of distinct polymer layers can lead to delamination during deep drawing.

At first sight the concept of incorporating a desiccant within a polymeric film to improve its barrier properties seems to be trivial. By precisely analyzing this problem many key factors have to be considered in order to create a highly efficient composite system. Previously published documents lack of essential information concerning the specific combination of desiccant-polymer pairs, which is essential for designing a high barrier material. Furthermore they lack the description of the production procedures, as well as the composite membrane characteristics like mechanical stability, WVTRs and especially deep drawing properties.

What is therefore needed is an improved polymer-desiccant composite film consisting of a specific combination of desiccant and polymer, which have a strong interaction allowing a better WVTR. This improved WVTR is important in particular for packaging in the pharmaceutical and medical industry and in particular for blister packaging.

BRIEF SUMMARY OF THE INVENTION

It is an object of the invention to provide a deep drawable, halogen free moisture barrier polymer-desiccant composite film with an initial water vapor transmission rate (WVTR) of below 0.05 g m^"2 day^"1.

The invention solves the posed problem with a polymeric film comprising the features of claim 1.

The advantages obtained by the polymeric film according to claim 1 are the following:

- The polymeric film comprising a desiccant-polymer combination exhibits a strong polymer-desiccant affinity leading to well dispersed desiccant particles within the polymeric matrix;

- the polymeric film has a water vapor transmission rate (WVTR) of less than 0.05 g rrf² day^"1 during its lag time;

- the film is deep drawable without delamination of the two layers; and

- the multiple layer film consists of a single kind of polymer.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a film material which creates an effective zero relative humidity within a package for the duration of a specific lag time, is deep drawable, transparent or translucent and has desirable mechanical properties in dry and soaked condition for applications as blister packaging material of pharmaceuticals. Many desiccants are known in the art ranging from silica gels, salts (magnesium sulfate, calcium chloride, sodium phosphate di-basic, ammonium chloride, potassium carbonate, potassium aluminum disulfate, magnesium chloride etc.) to zeolites.

The present invention uses a multiple layer film consisting of one single polymer for avoiding delamination complications while deep drawing. The active ingredient incorporated into the polymer matrix is preferably calcium oxide (CaO) and the polymer matrix is preferably a cyclic olefin copolymer.

Chemical desiccants can generally be divided into two groups, either desiccants which change the volume by absorption of water, or those who do not. CaO as chemical sorbent is mentioned amongst a variety of other desiccants, but is denoted as not very suitable due to the increase of volume upon water absorption and resulting crack formation and channeling problems. Surprisingly it was observed that no crack formation or reduction of the barrier upon expansion of the desiccant occurred, and even total agglomerate over 2 wt. % of CaO particles did neither substantially lower the film's barrier properties nor decrease its physical stability. The polymeric film according to the invention is designed as an at least two layer system, where the outer "shielding"- layer protects the desiccant contained within the second film. CaO particles which are dispersed within the cyclic olefin copolymer matrix were well embedded within the cyclic olefin copolymer matrix, (see fig. 1 ) which is a key feature.

A further key feature is, that the polymeric film according to the invention is designed as an at least two layer system, where the outer "shielding' -layer protects the desiccant contained within the second film. In case of a monofilm, consisting of CaO particles embedded within a polymeric matrix in the absence of an intact polymer shield layer comprising a good WVTR, the lag-time needed for the water-vapor to reach the desiccant is drastically reduced.

Further advantageous embodiments of the invention can be commented as follows:

In a special embodiment of the invention the polymer of the first and second layer is a cyclic olefin copolymer and both cyclic olefin copolymers are based on the same type of cyclic olefin and the same type of acyclic olefin. In a further embodiment the desiccant particles consist of a chemical desiccant, which increases its volume during adsorption of water, and preferably consists of CaO. The chemical desiccant - if not consisting of CaO - may preferably be present in amorphous form. The desiccant may also be a physical desiccant, preferably a zeolith. The mean particle size of the desiccant is purposefully below 2 pm, preferably below 0.5 pm.

Particle size distribution may be in the range of .01 pm - 5 pm. Surprisingly It was found that the small particle size leads to a better dispergation and homogenization of the particles, an improved transparency and an over all better efficiency regarding the water vapor barrier function.

The cyclic olefin on which the cyclic olefin copolymer is based is preferably norbornene. The acyclic olefin is preferably selected from the group of ethylene, propylene, butylene or mixtures thereof.

Most preferably the cyclic olefin copolymer is a copolymer of norbornene and ethylene. The norbornene may be present in an amount of x = 10 to 90 mole percent and the ethylene may be present in an amount of y = 100 - x mole percent. Preferably the norbornene is present in an amount of x = 15 to 30 mole percent and the ethylene is present in an amount of y = 100 - x mole percent.

The cyclic olefin copolymer may purposefully have a heat deflection temperature (HDT/B) of at least 50°C, preferably at least 60°C and most preferably of at least 75°C.

The cyclic olefin copolymer may purposefully have a heat deflection temperature (HDT/B) of at most 200°C, preferably at most 100°C and most preferably of at most

80°C.

The melt temperature of the cyclic olefin copolymer may purposefully be at least 190°C, preferably at least 230°C. The melt temperature of the cyclic olefin copolymer may purposefully be at most 320°C, preferably at most 250°C.

The glass transition temperature of the cyclic olefin copolymer is purposefully in the range of 30° to 200°.

The molecular weight of the cyclic olefin copolymer is purposefully higher than 50Ό00, preferably higher than 100Ό00. Purposefully the molecular weight of the cyclic olefin copolymer is lower than 180Ό00, preferably lower than 150Ό00.

The cyclic olefin copolymer may have an amorphous structure. The amount of desiccant particles in the second layer is preferably in the range of 20 - 60 weight- % of the total weight of the second layer.

The ratio T-i :T₂ of the thickness Ti of the first layer to the thickness T₂ of the second layer is preferably in the range of 1 :2 to 2: 1 .

The polymeric film may additionally comprise a third polymeric layer placed on the free surface of the second or first layer.

The first layer may consist essentially of polypropylene or polyethylene.

The polymeric film may be placed between two outer layers of a polymeric material. In case of single layers consisting of different types of polymers they may be connected to each other with suitable commercially available primers or adhesives.

The outer layers may be made of polyethylene and have a thickness each in the range of 10 - 50 pm.

Preferably the polymeric film may be essentially halogen-free.

The cyclic olefin copolymer has purposefully a water vapor transmission rate WVTR < 0.5 g mm m^"2 day^"1 and preferably≤ 0.3 g mm m^"2 day^"1 , measured at 75 % relative humidity difference at 40 °C.

The third layer of the polymeric film may comprise ethylene vinyl alcohol (EVOH) or polyvinyl alcohol (PVA). Surprisingly rhe addition of EVOH or PVA confers to the polymeric film the additional property of being an oxygen barrier to an extent of < 0.40 cm³ mm m^"2 bar^"1 d^"1.

The average thickness of the first and second layer is purposefully each in the range of 20 and 1000 pm , preferably in the range of 50 to 500 pm.

The average thickness of the polymeric film is purposefully more than 40 pm, preferably more than 100 pm. The average thickness is purposefully less than 1200 pm, preferably less than 800 pm. The cyclic olefin copolymer has purposefully a water absorption after immersion into water for 24 hours at 23 °C of less than 0.020 %, preferably of less than 0.012 %.

A further embodiment comprises a method of manufacture of the polymeric film according to the invention in which the first layer of the polymeric film is attached to the second layer of the polymer film by the solvent casting technique, whereby the first layer preferably consist essentially of a cyclic olefin polymer. The first layer of the polymeric film may also be attached to a third layer by the solvent casting technique.

A further embodiment comprises a method of manufacture based on the extrusion technique for attaching the first layer of the polymeric film according to the invention to the second layer or third layer.

A further embodiment comprises a method of manufacture based on the calandering technique for attaching the first layer of the polymeric film according to the invention to the second layer or third layer, whereby the first layer consists essentially of polypropylene.

The polymeric film according to the invention is useful for pharmaceutical and medical packaging, in particular blister packaging.

A BRIEF DESCRIPTION OF THE DRAWINGS

Several embodiments of the invention will be described in the following by way of example and with reference to the accompanying drawings in which:

Fig. 1 is a SEM image of a polymeric film according to the invention consisting of a three-layered sandwich film;

Fig. 2 is a graph of the water vapor transmission rate (WVTR) of a polymeric film; and Fig. 3 is a schematic section through a polymeric film according to the invention. The following examples clarify the invention further in more detail. Example 1

Production of a cyclic olefin copolymer / CaO dispersion

CaO particles with an average diameter of 400 nm (with a minimal diameter of 90 nm and a maximal diameter of 1170 nm) were dispersed in a cyclic olefin copolymer solution (10 wt % in xylene) with a weight ratio of 1 to 1 by ultra-sonication for 6 hours.

Production of three-layered sandwich films

First, a pure cyclic olefin copolymer film (10 wt % in xylene) was casted on a glass substrate by a spiral film applicator. After drying, this cyclic olefin copolymer layer was covered with a CaO-cyclic olefin copolymer dispersion having a weight ratio (CaO to cyclic olefin copolymer) of 1 :1. For sealing the desiccant containing layer, a third layer of pure cyclic olefin copolymer solution (10 wt % in xylene) was applied after the second film had been dried. This resulted in a sandwich structure comprising following layer thicknesses:

First layer of pure cyclic olefin copolymer: 30 pm

Second layer of cyclic olefin copolymer: comprising CaO: 32 pm

Third layer of pure cyclic olefin copolymer: 15 pm.

Properties of the polymeric films obtained

The polymeric films were deep drawable at temperatures between 70°C and 180°C. As shown on the left side of fig. 1 the top and bottom layers of the polymeric film consist of cyclic olefin copolymer; the intermediate layer consists of calcium oxide particles which are dispersed in a cyclic olefin copolymer matrix. At the right side of fig. 1 a magnification of the intermediate layer of the polymeric film is shown.

Fig. 2 shows the water vapor transmission rate (WVTR) of the polymeric film measured with a MOCON device at 40 °C and a relative humidity of 75% in dependence of time over 120 hours, The graph shows two individually measured three-layered samples obtained according to example 1. The WVTR measured for 120 hours remained essentially constant after 1 0 hours.

As shown in Fig. 3 the first layer (1 ) of the polymeric film consists essentially of a polymer chosen from the group of: cyclic olefin copolymer, polypropylene and polyethylene and a second layer (2) placed on the lower surface of the first layer (1 ), the second layer (2) comprising the same polymer as the first layer (1 ) as a matrix in which a plurality of desiccant particles (4) is embedded. The polymeric film is placed between two outer layers (3) of a polymer preferably a polyethylene.

Example 2

Production of a cyclic olefin copolymer / CaO Dispersion

CaO particles with an average particle diameter of 400 nm, with a minimal diameter of 90 nm and a maximal diameter of 1 170 nm were dispersed in a cyclic olefin copolymer solution ( 5 wt % in xylene) with a weight ratio of 1 to 2 by ultra sonication for 6 hours.

Production of three-layered sandwich films

First, a pure ethylene norbornene copolymer film (20 wt % in xylene) was casted on a glass substrate by a spiral film applicator. After drying, this ethylene norbornene copolymer layer was covered with a CaO-ethylene norbornene copolymer dispersion in a weight ratio of 1 to 2. For sealing the desiccant containing layer, a third layer of pure ethylene norbornene copolymer solution (20 wt % in xylene) was applied after the second film had been dried.

Example 3

Production of a cyclic olefin copolymer / CaO Dispersion

CaO particles with an average particle diameter of 400 nm, with a minimal diameter of 90 nm and a maximal diameter of 1 170 nm were dispersed in cyclic olefin copolymer solution (20 wt % in xylene) with a weight ratio of 3 to 4. Because of the increased viscosity, the dispersion was vigorously steered for 24 hours, followed by ultra sonication for 6 hours to reach the required homogenization, leading to films with good barrier properties.

Production of three-layered sandwich films

First, a pure cyclic olefin copolymer film (20 wt % in xylene) was casted on a glass substrate by a spiral film applicator. After drying, this cyclic olefin copolymer layer was covered with a CaO-cyciic olefin copolymer dispersion having a weight ratio (CaO to cyclic olefin copolymer) of 3 to 4. For sealing the desiccant containing layer, a third layer of pure cyclic olefin copolymer solution (20 wt % in xylene) was applied after the second film had been dried.

Example 4

Production of a cyclic olefin copolymer / CaO and polypropylen / CaO and polyethylene - low density / CaO

CaO powder with an average diameter of 100 pm was compounded into a cyclic olefin copolymer granulate with a CaO to polymer ratio of 2:5 by weight. Because of the increased melt flow index, the mixed compound was extruded with a single-screw extruder and a kneader-system to reach the required homogenization. The result was a film with good barrier properties.

Production of three-layered sandwich films

First, a pure cyclic olefin copolymer film or other olefin polymer was extruded in a multi slit die extrusion line or was laminated in a second stage process by a laminator line. For the lamination an adhesive layer is needed by coating or extrusion.

As a preferred cyclic olefin copolymer, ethylene norbornene copolymer was used in all four examples 1 - 4.

Claims

1 . Polymeric film useful as water vapor barrier comprising a

(i) first layer consisting essentially of a polymer chosen from the group of: cyclic olefin copolymer, polypropylene and polyethylene;

(ii) a second layer placed on one of the surfaces of the first layer, the second layer comprising a polymer chosen from the group of: cyclic olefin copolymer, polypropylene and polyethylene, as a matrix in which a plurality of desiccant particles is embedded;

characterized in that

the polymers of the first and second layer are of the same type.

2. Polymeric film according to claim 1 , characterized in that the polymer of the first and second layer is a cyclic olefin copolymer and that both cyclic olefin copolymers are based on the same type of cyclic olefin and the same type of acyclic olefin.

3. Polymeric film according to claim 1 or 2, characterized in that the desiccant particles consist of a chemical desiccant, which increases its volume during adsorption of water, and preferably consists of CaO.

4. Polymeric film according to one of the claims 1 to 3, characterized in that the desiccant particles are present in amorphous form.

5. Polymeric film according to claim 1 or 2, characterized in that the desiccant is a physical desiccant, preferably a zeolith.

6. Polymeric film according to one of the claims 1 to 5, characterized in that the mean particle size of the desiccant is below 2 μπι, preferably below 0.5 pm.

7. Polymeric film according to one of the claims 2 to 6, characterized in that the cyclic olefin on which the cyclic olefin copolymer is based is norbornene.

8. Polymeric film according to one of the claims 2 to 7, characterized in that the acyclic olefin is selected from the group of ethylene, propylene, butylene or mixtures thereof.

9. Polymeric film according to one of the claims 2 to 8, characterized in that the cyclic olefin copolymer is a copolymer of norbomene and ethylene.

10. Polymeric film according to claim 9, characterized in that norbomene is present in an amount of x = 10 to 90 mole percent and the ethylene is present in an amount of y = 100 - x mole percent.

1 1. Polymeric film according to claim 10, characterized in that norbomene is present in an amount of x = 15 to 30 mole percent and the ethylene is present in an amount of y = 100 - x mole percent,

12. Polymeric film according to one of the claims 2 to 11 , characterized in that the cyclic olefin copolymer has a heat deflection temperature (HDT/B) of at least 50°C, preferably at least 60°C and most preferably of at least 75°C.

13. Polymeric film according to one of the claims 2 to 12, characterized in that the cyclic olefin copolymer has a heat deflection temperature (HDT/B) of at most 200°C, preferably at most 00°C and most preferably of at most 80°C.

14. Polymeric film according to one of the claims 2 to 13, characterized in that the melt temperature of the cyclic olefin copolymer is at least 190°C, preferably at least 230°C.

15. Polymeric film according to one of the claims 2 to 14, characterized in that the melt temperature of the cyclic olefin copolymer is at most 320°C, preferably at most 250°C.

16. Polymeric film according to one of the claims 2 to 15 characterized in that the glass transition temperature of the cyclic olefin copolymer is in the range of 30° to 200°.

17. Polymeric film according to one of the claims 2 to 16 characterized in that the molecular weight of the cyclic olefin copolymer is higher than 50ΌΟΟ, preferably higher than 100Ό00.

18. Polymeric film according to one of the claims 2 to 17 characterized in that the molecular weight of the cyclic olefin copolymer is lower than 180Ό00, preferably lower than 150ΌΟΟ.

19. Polymeric film according to one of the claims 2 to 18 characterized in that the cyclic olefin copolymer has an amorphous structure.

20. Polymeric film according to one of the claims 1 to 19 characterized in that the amount of desiccant particles in the second layer is in the range of 20 - 60 weight- % of the total weight of the second layer.

21. Polymeric film according to one of the claims 1 to 20 characterized in that the ratio Ti:T₂ of the thickness Ti of the first layer to the thickness T2 of the second layer is in the range of 1 :2 to 2:1 .

22. Polymeric film according to one of the claims 1 to 21 , characterized in that it additionally comprises a third polymeric layer placed on the free surface of the second or first layer.

23. Polymeric film according to claim 22, characterized in that the first layer consists essentially of polypropylene or polyethylene.

24. Polymeric film according to one of the claims 1 to 23, characterized in that it is placed between two outer layers of a polymeric material.

25. Polymeric film according to claim 24, characterized in that the outer layers are made of polyethylene and have a thickness each in the range of 10 - 50 pm.

26. Polymeric film according to one of the claims 1 to 25, characterized in that it is essentially halogen-free.

27. Polymeric film according to one of the claims 2 to 26, characterized in that the cyclic olefin copolymer has a water vapor transmission rate WVTR≤ 0.5 g mm m^"2 day^"1 , preferably≤ 0.3 g mm nrf² day^"1 , measured at 75 % relative humidity difference at 40 X.

28. Polymeric film according to one of the claims 24 to 27, characterized in that the third layer comprises ethylene vinyl alcohol (EVOH) or polyvinyl alcohol (PVA).

29. Polymeric film according to one of the claims 1 to 28, characterized in that the average thickness of the first and second layer is each in the range of 20 and 1000 pm, preferably in the range of 50 to 500 pm.

30. Polymeric film according to one of the claims 1 to 29, characterized in that its average thickness is more than 40 pm, preferably more than 100 pm.

31. Polymeric film according to one of the claims 1 to 30, characterized in that its average thickness is less than 1200 pm, preferably less than 800 pm.

32. Polymeric film according to one of the claims 2 to 31 , characterized in that the cyclic olefin copolymer has a water absorption after immersion into water for 24 hours at 23 °C of less than 0.020 %, preferably of less than 0,012 %.

33. Method of manufacture of the polymeric film according to one of the claims 1 to 32, characterized in that the first layer is attached to the second layer by the solvent casting technique, whereby the first layer preferably consist essentially of a cyclic olefin polymer.

34. Method of manufacture according to claim 33, characterized in that the first layer is additionally attached to a third layer.

35. Method of manufacture based on the extrusion technique for attaching the first layer of the polymeric film according to one of the claims 1 to 32 to the second layer or third layer.

36. Method of manufacture based on the calandering technique for attaching the first layer of the polymeric film according to one of the claims 1 to 32 to the second layer or third layer, and wherein the first layer consists essentially of polypropylene.

37. Use of the polymeric film according to one of the claims 1 to 32 for pharmaceutical and medical packaging, in particular blister packaging.